Hierarchical models for service-oriented systems

We present our approach to the denotation and representation of hierarchical graphs: a suitable algebra of hierarchical graphs and two domains of interpretations. Each domain of interpretation focuses on a particular perspective of the graph hierarchy: the top view (nested boxes) is based on a notion of embedded graphs while the side view (tree hierarchy) is based on gs-graphs. Our algebra can be understood as a high-level language for describing such graphical models, which are well suited for defining graphical representations of service-oriented systems where nesting (e.g. sessions, transactions, locations) and linking (e.g. shared channels, resources, names) are key aspects

An Algebra of Hierarchical Graphs

We define an algebraic theory of hierarchical graphs, whose axioms characterise graph isomorphism: two terms are equated exactly when they represent the same graph. Our algebra can be understood as a high-level language for describing graphs with a node-sharing, embedding structure, and it is then well suited for defining graphical representations of software models where nesting and linking are key aspects

New long-lived particle searches in heavy-ion collisions at the LHC

We show that heavy-ion collisions at the LHC provide a promising environment to search for signatures with displaced vertices in well-motivated new physics scenarios. Compared to proton collisions, they offer several advantages: (i) the number of parton level interactions per collision is larger, (ii) there is no pileup, (iii) the lower instantaneous luminosity compared to proton collisions allows one to operate the LHC experiments with very loose triggers, and (iv) there are new production mechanisms that are absent in proton collisions We focus on the third point and show that the modification of the triggers alone can increase the number of observable events by orders of magnitude if the long-lived particles are predominantly produced with low transverse momentum. Our results show that collisions of ions lighter than lead are well motivated from the viewpoint of searches for new physics. We illustrate this for the example of heavy neutrinos in the Neutrino Minimal Standard Model

Reorganizing and integrating public health, health care, social care and wider public services:A theory-based framework for collaborative adaptive health networks to achieve the triple aim

Forty-one studies were included. Eight components were identified: social forces, resources, finance, relations, regulations, market, leadership, and accountability. Each component consists of three or more subcomponents, providing insight into (1) the (sub)component-specific strategies that accelerate PHM development, (2) the necessary contextual factors and mechanisms for these strategies to be successful and (3) the extracted theories that underlie the (sub)component-specific SCMO configurations. These theories originate from a wide variety of scientific disciplines. We bring these (sub)components together into what we call the Collabroative Adaptive Health Network (CAHN) framework

Extended Formulations in Mixed-integer Convex Programming

We present a unifying framework for generating extended formulations for the polyhedral outer approximations used in algorithms for mixed-integer convex programming (MICP). Extended formulations lead to fewer iterations of outer approximation algorithms and generally faster solution times. First, we observe that all MICP instances from the MINLPLIB2 benchmark library are conic representable with standard symmetric and nonsymmetric cones. Conic reformulations are shown to be effective extended formulations themselves because they encode separability structure. For mixed-integer conic-representable problems, we provide the first outer approximation algorithm with finite-time convergence guarantees, opening a path for the use of conic solvers for continuous relaxations. We then connect the popular modeling framework of disciplined convex programming (DCP) to the existence of extended formulations independent of conic representability. We present evidence that our approach can yield significant gains in practice, with the solution of a number of open instances from the MINLPLIB2 benchmark library.Comment: To be presented at IPCO 201

Transforming towards sustainable health and wellbeing systems:Eight guiding principles based on the experiences of nine Dutch Population Health Management initiatives

Introduction Population Health Management initiatives are increasingly introduced, aiming to develop towards sustainable health and wellbeing systems. Yet, little is known about which strategies to implement during this development. This study provides insights into which strategies are used, why, and when, based on the experiences of nine Dutch Population Health Management initiatives. Methods The realist evaluation approach was used to gain an understanding of the relationships between context, mechanisms and outcomes when Population Health Management strategies were implemented. Data were retrieved from three interview rounds (n = 207) in 2014, 2016 and 2017. Data was clustered into guiding principles, underpinned with strategy-context-mechanism-outcome configurations. Results The Dutch initiatives experienced different developments, varying between immediate large-scale collaborations with eventual relapse, and incremental growth towards cross-sector collaboration. Eight guiding principles for development towards health and wellbeing systems were identified, focusing on: 1. Shared commitment for a Population Health Management-vision; 2. Mutual understanding and trust; 3. Accountability; 4. Aligning politics and policy; 5. Financial incentives; 6. A learning cycle based on a data-infrastructure; 7. Community input and involvement; and 8. Stakeholder representation and leadership. Conclusion Development towards a sustainable health and wellbeing system is complex and time-consuming. Its success not only depends on the implementation of all eight guiding principles, but is also influenced by applying the right strategies at the right moment in the development